This application is related to Japanese application No. HEI11-216109 filed on Jul. 30, 1999, whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a resin-encapsulated semiconductor device and a process for fabricating the same. More particularly, it relates to a resin-encapsulated semiconductor device of a ball grid array (BGA) type which is called a chip size package (CSP), and a process for fabricating the same.
2. Related Art
Conventionally, resin-encapsulated semiconductor devices of the BGA type called CSP as shown in FIG. 9(c) have been widely utilized.
The resin-encapsulated semiconductor device comprises a wiring substrate 25 for mounting a semiconductor chip which includes thereon a patterned wiring 26, a plurality of first through holes 31 for external connection and a plurality of lands 27 for external connection which cover the entire openings of the first through holes 31 and partially constitute the patterned wiring 26, and a semiconductor chip 21 mounted thereon. The semiconductor chip 21 is electrically connected to the patterned wiring 26 through wire bonding using an Au wire 23. The semiconductor chip 21 and the Au wire 23 are encapsulated with a resin 22 for encapsulation. Further, external terminals 24 for external connection are mounted on a surface opposite to a chip-mounting surface of the wiring substrate 25 and electrically connected to the semiconductor chip 21 via the lands 27.
The resin-encapsulated semiconductor device is fabricated by the following process.
First, the first through holes 31 for mounting the external terminals are formed in an area array matrix of the wiring substrate 25.
On a surface of the wiring substrate 25 where the semiconductor chips 21 are to be mounted, the patterned wiring 26 and the lands 27 for external connection are formed of a conductive film, and marks 30 representative of cutting lines are formed of the conductive film in the periphery of the wiring substrate 25. The lands 27 partially serve as the patterned wiring 26 and cover the respective first through holes 31.
Then, the semiconductor chips 21 are mounted on the wiring substrate 25 and electrically connected to the patterned wiring 26 formed on the wiring substrate 25 through wire bonding using Au wires 23.
The semiconductor chips 21 arranged on the wiring substrate 25 and the Au wires 23 are all encapsulated in one-piece with the resin 22 by a transfer mold technique.
Then, the encapsulated semiconductor chips 21 are divided into individual chips. At this time, as shown in FIG. 9(a), a surface of the wiring substrate 25 where the external terminals are to be mounted is adhered to a jig 33 for fixing the wiring substrate. The chip-mounting surface of the wiring substrate 25 is faced upward so that the marks 30 of cutting lines can be observed from the chip-mounting surface side of the wiring substrate 25. The cutting line is defined by joining a pair of marks 30 formed on the opposite sides of the periphery of the wiring substrate 25. The resin 22 and the underlying wiring substrate 25 are cut and divided with a single cutting blade 29 along the cutting line in one operation as shown in FIG. 9(b).
Thereafter, as shown in FIG. 9(c), the external terminals 24 are mounted at the first through holes 31 from the external terminal mounting surface and subjected to a reflow process to metallically bond the external terminals 24 and the patterned wiring 26 or the lands 27. Thus, an end product is obtained.
In the above-described fabrication process, the semiconductor chips 21 encapsulated with the resin 22 on the wiring substrate 25 are divided into individual chips 21 by cutting. That is, the wiring substrate 25 and the resin 22 formed of different materials are cut in one operation with one cutting blade 29. Therefore, the cutting blade 29 is extremely worn out.
Further, since cut faces of the resin 22 and the wiring substrate 25 are in the same plane, the resin encapsulant 22 and the wiring substrate 25 may be separated from each other at an interface therebetween.
The present invention provides with a process for fabricating a resin-encapsulated semiconductor device comprising the steps of: (a) forming a plurality of first through holes for external connection in a substrate for mounting semiconductor chips; (b) forming a conductive film on a chip-mounting surface of the substrate and patterning the conductive film into a plurality of patterned wirings and a plurality of lands which cover the entire openings of the first through holes and partially constitute the patterned wirings; (c) mounting two or more semiconductor chips on the chip-mounting surface of the substrate; (d) mounting external connection terminals at the first through holes from a terminal-mounting surface opposite to the chip-mounting surface and connecting the semiconductor chips to the external terminals through the lands; (e) encapsulating the two or more semiconductor chips in one-piece with a resin encapsulant; (f) cutting the substrate with a first cutting blade from the terminal-mounting surface of the substrate; (g) cutting the resin encapsulant with a second cutting blade thinner than the first cutting blade; and (h) dividing the resulting substrate for the individual semiconductor chips.
Further, the present invention provides with a resin-encapsulated semiconductor device comprising; a substrate for mounting a semiconductor chip including thereon a patterned wiring, a plurality of first through holes for external connection and a plurality of lands which cover the entire openings of the first through holes and partially constitute the patterned wiring, a semiconductor chip mounted on the substrate, the semiconductor chip being encapsulated with a resin, and terminals for external connection being mounted on a surface opposite to a chip-mounting surface of the substrate and electrically connected to the semiconductor chip through the lands, wherein an edge of the substrate is positioned inside an edge of the resin for encapsulation.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.